Valve lapping questions

Mine were like that from sealed power. I lapped them, cleaned the seat/valve with rubbing alcohol and then I poured rubbing alcohol in the exhaust ports to check for leaking. I also shined a flash light through the exhaust port in a dark room to see if they leaked. None leaked from either test.
Compression was within a couple of pounds of each other across all 8 cylinders, being 140 -142.